Samille Biasi Miranda, Rosalia Maux de Carvalho Rodrigues, Caroline de Farias Charamba Leal, Fernanda Campos, Hugo Rafael de Souza Cavalcante, Priscylla Gonçalves Correia Leite de Marcelos, Marcos Antonio Japiassú Resende Montes, Rodrigo Barros Esteves Lins
Background: In-office dental bleaching is a common aesthetic procedure, and different application methods may influence laboratory and clinical outcomes. Objectives: This systematic review and meta-analysis evaluated the effects of applicator brush use compared with conventional application without a brush during in-office hydrogen peroxide bleaching. Methods: The review followed PRISMA guidelines and was registered in PROSPERO (CRD42023491451). Electronic searches were conducted in PubMed, Cochrane Library, LILACS, and OpenGrey for studies published until April 2026. Clinical and in vitro studies comparing bleaching gel application with and without an applicator brush were included. Outcomes included hydrogen peroxide concentration in the pulp chamber, bleaching gel consumption, color change, and tooth sensitivity. Risk of bias was assessed using RoB 2 for the randomized clinical trial and the Sarkis-Onofre tool for in vitro studies. Meta-analyses were performed using RevMan, and certainty of evidence was assessed using the GRADE approach. Results: Of 10,260 records identified, four studies met the eligibility criteria, including one randomized clinical trial and three in vitro studies. Quantitative synthesis was based exclusively on the three in vitro studies. The randomized clinical trial showed low risk of bias, whereas the in vitro studies presented methodological limitations. Meta-analyses showed no statistically significant differences between applicator brush and conventional application methods for hydrogen peroxide concentration in the pulp chamber or bleaching gel consumption, although pooled estimates showed a tendency toward lower values with applicator brush use. No significant differences were observed in color change outcomes assessed by ΔEab, ΔE00, or ΔWID (p > 0.05). Heterogeneity ranged from 0% to 99%, and the certainty of evidence for all outcomes was rated as very low. Conclusions: Based on predominantly laboratory evidence of very low certainty, applicator brush use may be associated with lower hydrogen peroxide concentration in the pulp chamber and reduced bleaching gel consumption; however, these findings should be interpreted cautiously, and the clinical relevance of this application method remains uncertain.